CO₂ capture with complex absorbent of ionic liquid, surfactant and water

A new kind of high efficiency and low cost CO₂ complex absorbent was studied. Through innovative research, imidazolium-based ionic liquid was mixed with an aqueous solution of a non-ionic surfactant. The absorption ability of each complex absorbent with different concentrations was tested under a condition of 20°C, from 0.1 to 0.6 MPa. The absorption capacity of CO₂ in absorbents increases with increasing pressure and concentrations of ionic liquids. Different aqueous ionic liquid-surfactant solutions had different CO₂ absorption, and the sequence was as follows: X-100 > TWEEN 80 > PEG 400. [emim] [OTf] was more likely to absorb CO₂ than the other four ionic liquids. All of the complex absorbents had good absorption properties. The best combination was made up of 5% TWEEN 80, 10% [emim] [OTf] and water, which could capture 0.798 mol L^-1 CO₂ at 0.6 MPa while pure water could only capture 0.439 mol L^-1 under the same conditions. Through computer numerical simulations, the experimental data could be well fitted with Henry's law and Langmuir isothermal adsorption equation. After multiple absorption and regeneration, the absorption capacity of the complex absorbent was reduced by less than 5%. It could be expected to be a new type of CO₂ capture absorbent.